Journal of the Korean Society for Heat Treatment (열처리공학회지)

The Korean Society for Heat Treatment (한국열처리공학회)
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Change in Microstructure with the Gas Quenching Rate during Austempering Treatment of SAE 1078 Steel

SAE 1078 강의 오스템퍼링 열처리시 가스 퀜칭 속도에 따른 미세조직의 변화

  • Gi-Hoon Kwon (Heat & Surface Technology R&D Group, Korea Institute of Industrial Technology) ;
  • Hyunjun Park (Heat & Surface Technology R&D Group, Korea Institute of Industrial Technology) ;
  • Kuk-Hyun Yeo (Heat & Surface Technology R&D Group, Korea Institute of Industrial Technology) ;
  • Young-Kook Lee (Department of Materials Science and Engineering, Yonsei University) ;
  • Sang-Gweon Kim (Heat & Surface Technology R&D Group, Korea Institute of Industrial Technology)
  • 권기훈 (한국생산기술연구원 뿌리산업기술연구소 친환경열표면처리연구부문) ;
  • 박현준 (한국생산기술연구원 뿌리산업기술연구소 친환경열표면처리연구부문) ;
  • 여국현 (한국생산기술연구원 뿌리산업기술연구소 친환경열표면처리연구부문) ;
  • 이영국 (연세대학교 신소재공학과) ;
  • 김상권 (한국생산기술연구원 뿌리산업기술연구소 친환경열표면처리연구부문)
  • Received : 2023.05.08
  • Accepted : 2023.05.21
  • Published : 2023.05.30
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Abstract

When high carbon steel is heated in an appropriate austenizing temperature range and subjected to austempering, the size and shape of lamellar structure can be controlled. The high carbon steel sheet having the pearlite structure has excellent elastic characteristics because it has strong restoring force when properly rolled, and is applied in a process known as patenting-process using lead bath. In the case of isothermal treatment using lead-medium, it is possible to quickly reach a uniform temperature due to high heat transfer characteristics, but it is difficult to replace it with process technology that requires treatment to remove harmfulness lead. In this study, we intend to develop fluidization technology using garnet powder to replace the lead medium. After heating the high-carbon steel, the cooling rate was changed by compressed air to the vicinity of the nose of the continuous cooling curve, and then maintained for 90 s and then exposed to room temperature. The microstructure of the treated specimens were analyzed and compared with the existing products treated with lead bath. The higher the flow rate of compressed air, the faster the cooling rate to the pearlite transformation temperature, so lamellar spacing decreases and the hardness tends to increase.

Keywords

Acknowledgement

이 성과는 산업통상자원부(MOTIE)와 한국산업기술평가관리원(KEIT)의 재원을 받아 수행된 연구입니다(No. 20014673).

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